Transfer factors, which are produced by leukocytes and lymphocytes, are small water-soluble polypeptides of about 44 amino acids that stimulate or transfer cell-mediated immunity from one subject to another and through species, but it does not provoke an allergic response. Since the transfer factors are smaller than antibodies, they do not transfer antibody-mediated responses, they are non-immunogenic so they do not induce the production of antibodies. Properties and characteristics of transfer factors have been discussed in U.S. Pat. Nos. 4,816,563, 5,080,895, 5,840,700, 5,883,224, and 6,468,534 patents.
Transfer factors have been described as effective therapeutics for treating herpex simplex virus infection, to treat acne, and for the treatment of infections caused by Candida albicans. Also, they have been used to treat cryptosporidiosis in recipients treated with a specific transfer factor. On the other hand, they have also been used for the treatment of small pox, as a pretreatment of children having transfer factor from subjects who had small pox.
For many years diverse methodologies have been used to obtain the transfer factor. For example, patent application WO2007143957 describes a process for obtaining the factor from leukocytes; this process includes the following steps: adjusting the leukocyte homogenate, dialysis and/or ultrafiltration, concentration by lyophilization, adjusting the raw medical solution, interoperative testing, homogenization, prefiltration, ultrafiltration, sterilization by filtration, thermal inactivation, product packaging, and lyophilization. However, in said process a highly raw factor is obtained, since it contains a large number of components that may mask the factor action.
In turn, NLA2004000058 patent describes a method wherein a leucocitary extract is subjected to sterilization by filtration, and chromatography using Sephadex G-15. This process uses as a quality control the chemotaxis test in rat peripheral blood or thymus and spleen lymphocytes. However, as said method is subjected only to a separation by sephadex, it does not guarantee the purity of the factor since it contains multiple components that can interfere with the metabolic action of the factor.
On the other hand, patent application No. US20030031686A1 describes a method for obtaining a transfer factor from chicken eggs. This method consists in immunizing the birds with a particular antigen and from the egg white to obtain a water soluble fraction; this fraction was subjected to three consecutive filtration processes: a) by filter paper, (b) by vacuum using glass-fiber filter, and c) by filtration using a DURAPORE hydrophilic membrane to remove lipids and lipoproteins. The protein-containing fraction is collected, frozen, and lyophilized. Although, this process is extremely simple, it has the drawback of lacking of a low molecular weight polypeptide separation, and therefore the product obtained contains proteins interfering with the transfer factor action.
Another process to obtain transfer factor is that described in the US20020044942 patent application. Said process consists in obtaining the factor from immunized-chicken eggs, and comprises various steps, including filtration, centrifugation, filtration, dialysis, high-performance liquid chromatography, and lyophilization. However, the disadvantage of this process is the difficult handling of eggs when manually separating the yolk and the white, resulting in the protein fraction becoming contaminated with the lipid fraction.
Likewise, U.S. Pat. No. 5,840,700 patent describes a method to obtain a substantially pure transfer facto with a specific activity of at least 5000 units per AU214. The process consists mainly in contacting a sample containing the transfer factor with an immobilized antigen to which the factor binds specifically under conditions favoring the formation of the antigen-transfer factor complex. This complex is subsequently separated by reverse phase, high-resolution liquid chromatography, and high-resolution liquid chromatography by gel filtration. Despite the high degree of purity due to the antigen-specific immobilization step, this process has the great disadvantage of requiring a large amount of antigen, resulting in a fairly expensive process.
Finally, EP0143445A2 patent application describes a method for obtaining a transfer factor from lactating-cows' colustrum. This method basically consists of the following steps: centrifugation to obtain a cell precipitation, removal of casein, ultrafiltration, and dialysis, chromatography, and lyophilization. This process has the great disadvantage of the low availability of caws' or other mammals' colostrum in lactation stage.